Helium Vapor Cooled Current Leads

Abstract

A new technique is described for constructing vapor cooled leads used to introduce electrical currents into liquid helium. Using this method, leads can be constructed to carry optimum currents ranging from low values (less than 100 A) to very high values (several thousand amperes). The current carrying elements are small (No. 38) silver‐plated copper wires woven into the shape of cylindrical tubes (i.e., electrostatic shielding). This fine division of the current carrying elements allows very good heat exchange with the helium boil‐off gas. Helium losses are approximately 2.71×10⁻³ liter/h A for a pair of leads operating at the optimum current.